my scenario / use case is
I have this list of records: <timestamp>: <number>\n (hiking)
and want that turned into sparklines or something similar
I create a wiki "fnd_macros", in there I create a tidddler "sparklines"
then I add a reference like fnd_macros/sparklines in the body of the respective tiddler
so fnd/hiking reads <timestamp>: <number>\nscript:fnd/plugins
normally that ends up being ignored
then I create a whilelist in my home space, so fnd/_plugins reads fnd_macros/sparklines
if that's in there, the corresponding script tag to the referenced macro tiddler is emitted
{{script:wiki/title}} might work, essentially pretending this was transclusion
in which case you could work within the existing syntax:
{{script:title}}@wiki
from IRC (edited for conciseness):